Fast neutron and mixed (neutron/photon) beam teletherapy for grades III and IV astrocytomas

Abstract

A study was performed in order to assess the efficacy of using fast neutron irradiation, either alone or in conjunction with megavoltage photons, in treating Grades III and IV astrocytomas. The study encompasses fifteen patients with Grade III lesions and twenty-two patients with Grade IV lesions. Various fractionation schemes are described. Only one patient is still alive at the present time. Regarding the other patients, the mean survival after completing therapy was 10.8 months for those patients with Grade III lesions and 7.5 months for those patients with Grade IV lesions. Particularly for Grade III lesions, the average survival was appreciably less than that of patients treated with photons alone. The treated patients also had no noticeable improvement in quality of survival when compared with the results of conventional photon irradiation. There was no appreciable difference in survival between the group treated with neutrons alone or with mixed (neutron/photon) irradiation. Autopsy data on fifteen patients showed gross tumor progression in only one instance, and this patient also had liver metastases. In the other fourteen cases, the gross tumor volume was replaced by coagulation necrosis. In general, there were some abnormal cells intermixed with the regions of coagulation. These cells are currently felt to be reactive astrocytes. Both a diffuse gliosis and a white matter demyelination were found in regions far from the tumor volume and this presumably is related to the ultimate cause of death.